Method for the manufacture of a sensor element

ABSTRACT

The invention relates to a method for the manufacture of a sensor element and to a sensor element. In the method, both surfaces of a sensor film are provided with metallic electrodes. The sensor element is produced by cutting it from a larger amount of sensor element material. In the manufacture of the sensor element material, the electrodes are produced as a continuous process from roll to roll and the sensor element material is formed by laminating as a continuous process from roll to roll. At least the signal electrode consists of repeated electrode patterns which are at least partially connected to each other via one or more narrow connecting strips, and a sensor element of a desired length and/or shape is produced by cutting the material across the region of the connecting strips.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for the manufacture of anelectromechanical sensor element and to a sensor element.

2. Description of the Related Art

Previously known is a so-called electret field, i.e. a permanentelectric charge injected into a dielectric material by ionizing. A filmapplicable for use as a sensor film in the sensor element of theinvention is presented in U.S. Pat. No. 4,654,546, in which a dielectricplastic film, such as polypropylene, containing flat or torn gas bubblesis used to form a so-called electret bubble film. Both surfaces of thefilm are metal-coated. WO specification 96/06718 presents a method forswelling a foamed plastic film, whereby the amount of gas contained inthe film can be more than doubled. Patent specification Fl 913741presents various electric structures for sensor elements. Previouslyknown are also fibrous polarized electret films, as presented e.g. inU.S. Pat. No. 4,874,659. Other known elements applicable in the sensorelement of the invention are piezoelectric sensor films, such as PVDF.

Sensor elements and sensor bands as provided by the invention, whichhave a relatively large area or length, connected to a suitable signalprocessing apparatus or system, can be used for many different purposes.Possible applications are for example sensors installed in a roadstructure for determining the weight of a moving vehicle, registrationand monitoring of a patient's vital functions (breathing, heartbeat andsnoring) using a sensor placed in the bed under the mattress e.g. inconjunction with sleep research, monitoring of the vital functions of adrunken person by means of a sensor installed in the floor of a jail,sensors mounted under a carpet in an old-age home to monitor an oldperson's getting up from bed, sensors mounted under a floor coating inthe vestibule of a bank or shopping center and connected to an alarmsystem. From a long sensor band installed on a fence around anindustrial area, using suitable software, it is possible to obtain bothcontact data and position data when both ends of the sensor band areconnected to a signal processing device. A sensor element may also bemounted inside a floor structure under a large machine, such as a papermachine, to monitor its operation. They can also be used in varioussafety applications, e.g. to make sure that a machine will not bestarted before its operator is in the proper place, and so on. Inaddition, this type of sensor elements can be used in sports e.g. tomeasure the force and duration of exertion. They can also be used asdifferent kinds of switches, such as light switches, or in underwaterultrasound measurements. Moreover, a signal, e.g. an ultrasound signalcan be fed into the sensor to make it vibrate. Sensors according to theinvention can also be used in various keyboards, in cages for testanimals for the measurement of motional activity, monitoring of thevital functions of an animal recovering from a surgical operation, andso on. Typically, when such large sensor elements are applied, aplurality of sensors are used and the signals obtained from them can becompared and summed to eliminate unnecessary signals or to draw otherconclusions, e.g. by installing several sensors in the floor of the samespace it is possible to eliminate e.g. signals produced by the vibrationof an air conditioner or the building itself and pick out the breath andpulse of a person lying on the floor.

Traditionally, this type of large sensor elements or bands have beenmanufactured by cutting a sensor element of a size suited for theintended use e.g. from sensor material coiled up on a roll andconsisting of a metal film with sensor films, e.g. electrically chargedelectret bubble films, laminated on its both surfaces so that thepositively charged sides lie against the metal film, with further metalfilms laminated against the negative side on the outer surfaces of thelaminate thus formed. When a force is applied to such an element, anelectric charge is generated between the signal electrode in the coreand the earth electrodes on the outer surfaces. A metal electrode mayalso be placed directly on the surface of the sensor film, e.g. byevaporating, as described e.g. in U.S. Pat. No. 4,654,546. Anothercommonly used method is to print an electrode pattern of silver paste onthe surface of a polyester film and laminate it together with a sensorfilm. With the first-mentioned methods, a problem in the manufacture oflarge sensor elements like this is that the sensors are sensitive toelectromagnetic interference and discharges of static electricity. Thisis due to the fact that, as the sensor is cut from material in which thesignal electrode is of the same size with the sensor material, itextends to the very edges of the sensor element. Therefore, the edgeareas of the elements need to be separately provided with metal filmsextending over the edges, these metal films being grounded. Another bigproblem is that when the material is being cut, the small metalparticles released during cutting are apt to form a short circuitbetween the signal electrode and the earth electrode. When the electrodesurfaces are made from silk-screen printed silver paste, the pricebecomes very high as silver paste is very expensive. As compared withthe manufacturing method of the invention, the price of an electrodesurface printed with silver pasta is multiple times higher.

The object of the present invention is to eliminate the drawbacks ofprior-art technology and to achieve a new manufacturing method thatmakes it possible to manufacture sensor material in an economic andenvironmentally friendly manner via mass production as continuousmaterial from which it is possible to cut interference-free sensorelements that are suited for many uses and applications as desired. Theinvention also concerns a new technique for making connections tosensors according to the invention.

BRIEF SUMMARY OF THE INVENTION

In the method of the invention, both outer surfaces of a sensor film,such as a dielectric bubble film, in which a permanent electric chargehas been injected by ionizing and which may also consist of a number offilms glued together, are provided with film-like metal electrodes, andthe outer surface of at least one of the metal electrodes is providedwith a film-like dielectric material, which may also consist of the sameelectromechanical sensor film. In the method, a sensor element isproduced by cutting it from a larger amount of sensor element materialin which at least the signal electrode has a patterned design.

The sensor element material according to a preferred embodiment of theinvention can be cut at short distances into pieces of suitable size foreach application, both crosswise and lengthways if necessary.Connections to the sensor material can also be easily made usingadvantageous tools as provided by the invention. A perforated sensorelement according to an embodiment of the invention can also be reliablymounted on the surface of a finished concrete floor or, during casting,inside the floor. The method of the invention is characterized by whatis said in the claims below.

An embodiment of the invention is characterized in that repeatedelectrode patterns are formed at least in the signal electrode material,said patterns being connected to each other via one or more narrowconnecting strips but otherwise disposed in separation from each other,and that the sensor element is formed from sensor element material bycutting the element into a desired length across the region of aconnecting strip.

An embodiment of the invention is characterized in that a connection tothe zero, ground and signal electrodes of the sensor is made by cuttingoff pieces of the zero and ground electrodes from the outermost layerson opposite sides using a tool as provided by the invention. The toolmakes a cut with a great accuracy, of the order of 5/100 mm, to adesired depth, allowing a connection to be made to the signal electrodein the core using a reliable crimp connector or rivet.

Another embodiment of the invention is characterized in that, in certainareas on the signal, ground and zero electrodes, a small spot on thealuminum electrode has been printed with silver paste to ensure aconnection as reliable as possible.

In a preferred embodiment of the invention, a typical feature is thatits signal, ground and zero electrodes are manufactured by a silk-screenprinting technique or by printing (e.g. ink jet printing), using e.g. adielectric material dryable by UV light, an electrode pattern on thesurface of the metal film placed on the dielectric film and etching offthe portions outside the pattern. Both the printing, drying, etching andwashing of the electrode pattern are performed in a roll-to-rollprocess. Likewise, the gluing together, i.e. lamination of the electrodematerial and the active electromechanical film is performed in aroll-to-roll process.

In an embodiment of the invention, in which the sensor element needs tobe fastened as reliably as possible to the surface of a concrete floor,the element is provided with holes at regular distances, allowing theelement to be fastened using a thin liquid cement-based putty for theleveling of concrete floors as it can stick directly to the floorsurface via the holes. Such a sensor element can also be embedded insidea concrete casting at the casting stage and fastened to thereinforcements.

Another essential feature of a preferred embodiment of the invention isthat the electret bubble film has been swelled before being charged,e.g. in a manner as described in WO publication 96/06718, therebyincreasing the amount of gas contained in it to a level exceeding 50%.When the film is then charged, its sensitivity after the swelling isincreased to a value multiple times higher than for a film withoutswelling.

Further, when an electret bubble film is used, the invention ischaracterized in that the sensor element has been subjected to intensiveaging by storing it for several days at a temperature slightly over thedesired operating temperature, e.g. at 65° C. when the desired maximumoperating temperature is 60° C., the sensitivity of the sensor beingthereby lowered as compared with the initial situation to a level of theorder of 20–25% of the original sensitivity. This makes the sensor verystable for the desired maximum operating temperature. The storagetemperature and period depend on the desired operating temperature. Innormal conditions, a pre-aging treatment lowering the sensitivity by 50%as compared with the initial level is sufficient.

By the method of the invention, sensor element material can bemanufactured fast and economically via mass production and coiled up inrolls, from which the material can be cut into pieces of desired lengthand width to form interference-free and reliable film-like sensorelements. In addition, the method of the invention, when aluminumelectrodes are used, allowing the etching to be performed using ironchloride, is very economic and environmentally friendly.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in detail by the aidof an example with reference to the attached drawings, wherein

FIG. 1 presents a sensor element according to a preferred embodiment ofthe invention in lateral section,

FIGS. 2 a and 2 b present the signal electrode of a sensor elementaccording to the invention in top view,

FIGS. 3 a, 3 b, and 3 c illustrate the production of signal electrodematerial,

FIG. 4 illustrates the patterning of the sensor band material, whichallows the sensor to be cut at desired distances to make it shorterand/or narrower.

FIGS. 5 a–5 c present tools for making connections to the sensorelement,

FIG. 6 presents a sensor material with a serpentine signal electrode,and FIG. 7 presents the signal electrode of a band-like sensor elementthat produces reliable position data.

DETAILED DESCRIPTION OF THE INVENTION

A typical film-like sensor element according to the invention has a thinsensor film 1, e.g. an electret bubble film having a thickness of 0.07%mm, in the middle inside the element as shown in FIG. 1. Placed aboveand below the sensor film 1 are thin, e.g. 0.1 mm thick polyester films2, 3 and 4. Films 2 and 3 are provided with thin aluminum films 5 and 6of a thickness of e.g. 0.009 mm laminated on their sides facing thesensor film 1. The aluminum film 6 on the surface of film 3 facing film1 is provided with patterns having the shape of pattern 41 presented inFIG. 2 a. The aluminum film 5 on the surface of film 2 forms acontinuous band-like pattern having a width of e.g. of the order of 50cm, which preferably is wider than the pattern 41 on the surface of film3. On the surface of film 4 there is likewise an aluminum film 7identical to film 5, placed against film 3. Aluminum film 6 functions asthe signal electrode of the sensor element. Aluminum film 5 functions asa zero electrode, i.e. reference electrode. Aluminum film 7 functions asa ground electrode, protecting the sensor against electromagneticinterference and static electricity discharges. Typically, aluminumfilms 5 and 7 are connected together, in which case they both also actas ground electrodes. The above description represents a preferredstructure of the invention. It is also possible to use an arrangement inwhich the core of the sensor consists of a dielectric film with apattern like pattern 41 provided on both of its outer surfaces, or evenan arrangement in which the core merely consists of a thin metal filmwith patterns corresponding to pattern 41 made in it by etching.Laminated on either side of this core is a sensor film 1, and the outersurfaces of these two sensor films are provided with earth electrodes,which in this case are also zero electrodes. Another possiblearrangement is one in which the aluminum film on the surface of film 2has been patterned in a manner corresponding to pattern 41 and a filmcorresponding to film 4 with a ground electrode 7 on its surface hasbeen laminated against film 2. In this case the result is a differentialsensor. The aluminum electrodes against the sensor film function assignal electrodes, one positive and the other negative, while the outeraluminum films function as earth electrodes. FIGS. 2 b and 7 present analternative, band-like signal electrode patterning. Sensor material likethis can be cut lengthwise to make narrow sensors of a length ofhundreds of meters if necessary.

In the manufacture of sensor material (FIG. 3 a), a dielectric/metalfilm 33 is used in which the supporting structure 34 is e.g. a polyesterfilm, but which may also consist of polyethylene or polyimide or someother dielectric film suited for the purpose. The sensor material ismade by first laminating on the surface of film 33 a metal film 35,which preferably is of aluminum but which may also be a copper film,which may be later provided e.g. with tinning. However, it is moreenvironmentally friendly to use aluminum film as it can be etched usingiron chloride, the disposal of which produces less environmental stressthan e.g. the substances used in the etching of copper. Thedielectric/aluminum film 33 is unreeled from a roll 31 and it passesunder a screen printing screen 37. By means of the screen, a desiredpattern 39 is printed on the film from dielectric material 36 dryablee.g. by UV light. Each time a print has been made, the film is movedthrough a desired distance, yet a distance somewhat shorter than thepattern printed, successive prints thus partially overlapping. Thepattern has been so designed that it allows repeated patterns to beprinted. Instead of silk screen printing, it is also possible to use adevice like an ink jet printer which prints the pattern on the film intiny droplets. After the pattern has been printed, the film is movedforward through a desired distance, through an UV drying oven 38 and isfurther coiled up on a roll 32. In this manner, a repeated pattern canbe printed. In a corresponding manner, an electrode can be printed withsilver paste on the surface of a clean dielectric film. However, this isconsiderably more expensive than the above-described method of etchingthe pattern from the aluminum film. After the desired pattern has beenprinted on the surface of the electrode film using a dielectric materialthat can withstand etching with iron chloride, the film roll 32 istransferred to an etching and washing line (FIG. 3 b), where the metalin the metal surface 35 of the film 34 in the areas not covered by thedielectric film 36 is first etched away using iron chloride, leavingelectrodes like e.g. those presented in FIGS. 2 a and 2 b on the film.After this, the films are washed using e.g. a sodium hydroxide solution38, which dissolves the printed dielectric material 36 away. Theresulting film 33 is a finished film of electrode material. The zero andearth electrode film materials are manufactured in a correspondingmanner. Further, the electrode material thus produced, in a mannercorresponding to the printing of dielectric material, can be printedwith silver paste in the areas where connectors are to be connected toensure a good electrical contact in a crimp connection. In this way, avery small amount of expensive silver is consumed as compared withprinting the entire electrode surface with silver paste.

After this, all the films are laminated together using a roll-to-rolllaminating apparatus (FIG. 3 c). For example, referring to FIG. 1 at thesame time, first the sensor film 1, which in a preferred embodiment ofthe invention is an electret bubble film, and the dielectric/metal film3, which has been manufactured by the method illustrated by FIGS. 3 aand 3 b, are laminated together. The aluminum electrode side 6, whichhas been provided with a desired signal electrode pattern 39, and thesensor film 1 go against each other. In laminating the films together,glue 61 is applied e.g. to the sensor film 1 using a raster roller 62,after which the films are rolled together between rollers 63 and 64. Thetwo films glued together are further rolled up on a roll 65. After this,still referring to FIG. 1, the film 2 with a zero or reference electrodepattern provided in the aluminum film 5 on one of its outer surfaces islaminated onto the laminate thus obtained. Further, to the laminate thusobtained, film 4, i.e. the earth electrode 7 is correspondingly added bylaminating against film 3. As a final result, sensor film material aspresented in FIG. 1 is obtained. From this material, sensor elements ofa desired length are cut using a cutting device suited for the purpose,e.g. a knife. By the method of the invention, in which preferably arepeated pattern is used, it is thus possible to produce sensor elementsof a very large length, even hundreds of meters, which consist of aplurality of sections connected together, yet with all their edges wellprotected against interference.

To a sensor according to the invention, connection leads can be reliablyconnected using crimp connectors to which the connection leads can beconnected e.g. by soldering or crimping. For the crimp connectors, whichare pressed through the whole sensor laminate and which thereby form anelectric connection to the electrodes, the signal, earth and zeroelectrodes have been provided with areas to which the connectors can bepressed without creating a short circuit between the signal electrodeand the earth/zero electrode. Typically, a sensor element according tothe invention (FIG. 4) comprises a lug 44 extending laterally from thesignal electrode and consisting of e.g. a wider continuous portion atthe end of three leads having a width of the order of 1 mm, to whichportion it is possible to connect several crimp connectors, manufacturede.g. by Nicomatic and Berg Electronics, to provide a reliable contact tothe signal electrode. When a long sensor element is to be produced, theextra lugs 44 are cut off, thus avoiding interference through these. Theearth and zero electrodes 5, 7 are so arranged that they extend in alateral direction beyond the normal width of the signal electrode andfurther to the area of these three narrow leads. Thus, when the widecontinuous portion is cut off, no extra interference will be producedbecause the total cross-sectional area of these three narrow leads inrelation to the entire length of the side of the sensor is negligible.Further, as their cross-sectional area is so small, a tiny metalparticle that may be released when the material is being cut will notcause a short circuit. The connections to the earth and zero electrodesare made using corresponding crimp connectors placed next to the lug 44.The leads are then connected to the crimp connectors e.g. by soldering.

Using the technique of the invention, it is also possible to produce anelement consisting of one or more sensor bands by arranging the signalelectrode pattern so that, when the etching dielectric is being printed,a continuous band-like pattern 28 (FIG. 2 b) is created. An alternativepatterning of the narrow band-like sensor material is presented in FIG.7, in which the connecting strips 49 are of a zigzag design. The widthof the signal electrode band may be e.g. 10 mm and the spacing betweenthem may be e.g. 20 mm. When a roll containing continuous sensor bandpatterns like this and also comprising earth and zero electrodeslaminated to it is cut lengthways along the midlines between the signalelectrode bands, sensor bands with a good protection againstinterference and, in the present case, having a width of 20 mm and a10-mm active area are obtained. If desirable, when laminating the filmstogether, it is possible to use glue that allows the end of the sensorband to be opened and the film layers to be detached from each other sothat the electrode surfaces can be cleaned. Thus, the connection leadscan be connected directly to different electrode layers.

The connections to a sensor element (FIGS. 2 b, 4 and 7) according to apreferred embodiment of the invention with no separate lugs 44specifically provided in it are made by cutting holes of a diameter ofe.g. 15 mm in the outermost dielectric film layers 2 and 4, which haveearth and zero electrodes 5 and 7 disposed on their inner surfaces, atany point where the innermost electrode is a signal electrode 44 or 28.The holes are cut using tools 71 and 72 according to the invention,manufactured for this purpose, as presented in FIG. 5 a. Pieces of theearth and zero electrodes are cut off from opposite sides, whereupon itis possible to make connections to the signal electrode using crimpconnectors or rivets. The tools 71 and 72 consist of two round pinshaving diameter of e.g. 20 mm. The pin 71 has an extension pin 73 of adiameter of e.g. 4 mm at the center of its end, and the other pin has acorresponding central hole 74, so one of the pins will go partiallyinside the other. Each pin has a circular cutting edge 75 of a diameterof 15 mm and a height of e.g. 0.1 mm when dielectric/metal films of athickness of 0.085 mm are used. Now, after a hole 76 having, in thepresent case, a diameter of 4 mm has been first made in the sensorelement using e.g. a suitable bayonet-type tool and the pins areinserted against each other through the said hole and pressed againsteach other and rotated at the same time, the cutting edges will cut intothe sensor to a depth such that the outermost films and the metalelectrodes on them are incised and can be removed from theabove-mentioned area 77 having a diameter of 15 mm while the signalelectrode 41 at the core remains intact (FIGS. 5 b and 5 c). Further,into this 4-mm hole is inserted a metallic tubular rivet 78, which, whenpressed into place, will spread out to the very edges of the hole, thusmaking a contact 79 to the signal electrode. Under the rivet, astiffening plastic washer 80 may be used on one side of the elementwhile a toothed metallic washer 81 is placed on the other side to ensurea reliable contact. The rivet is provided with a lug 82 to which a leadcan be connected by crimping or welding. In the edge area of the band,where there is no signal electrode at all, a hole is made in acorresponding manner and a rivet is pressed into it to make a connectionto the earth and zero electrodes.

The patterning of the element can be implemented as desired according tothe intended use. In a manner corresponding to the patterns of thesignal, earth and zero electrodes, it can also be provided with anantenna pattern if the sensor is used in a system involving theidentification of an object producing an effect on the sensor or othertype of identification using a so-called micro-tag, in which the antennapattern picks out an individual signal of the micro-tag. Such anembodiment may be applicable e.g. in the measurement of sportsperformances, identification of a patient or identification of a vehiclepassing over the sensor. The antenna pattern is preferably made on anextra dielectric/metal electrode film 33 laminated on the surface of thesensor element. The connection of a lead to the electrode can beimplemented in a manner corresponding to the case described above.Instead of a tubular rivet, all the lead connections can also be madeusing crimp connectors having a plurality of small teeth that penetratethe material, as are manufactured e.g. by Nicomatic.

FIG. 4 presents a part of the signal electrode of a preferred sensorelement material according to the invention, which is applicable formany uses. Here, the signal electrode consists of checks 44 of a smallsize, e.g. 25×25 mm, with a relatively wide gap 47 between them. Thechecks are connected together by one or a few very narrow connectorstrips 46. The checks may naturally also comprise round shapes, e.g.their corners may be rounded, or they may also be completely circular.They may also be of a triangular shape or they may have more than fourcorners. From such a sensor element, it is easy to produce sensors of adesired shape, e.g. floor sensors by cutting the sensor element into thedesired shape using a corresponding grid or other alignment patternarranged on the outer surface of the sensor element as an aid. Thus, itis possible to arrange for a connecting strip of a width of one check torun continuously from a sensor element mounted in the actual place ofuse to a wall and further up along the wall. This arrangement obviatesthe need to provide a connection lead under a carpet, where it would bereadily visible and exposed to damage; instead, a completelyunnoticeable floor sensor is achieved. A connection to such a sensor canbe made in the manner described above. Further, a sensor elementmaterial with a signal electrode patterned in this manner can beprovided with small holes 48, e.g. of a diameter of 10 mm, by punchingby a roll-to-roll technique at regular distances in the areas 47 betweenthe checks 44. Via such holes, the sensor element can be fastened to aconcrete floor by means of surface leveling putty, which will fastendirectly to the concrete in the area of the holes.

The cutting of the outermost layers without damaging the signalelectrode can also be performed using a cutting device consisting of apair of self-locking pliers with jaws, handles and a locking part forlocking the jaws to a desired distance between them. The lower jaw isfitted with a horizontal metal plate and the upper jaw with a verticalcutter. Using such a cutting device, the earth and zero electrodes canbe cut off from the sensor element by adjusting the cutter exactly tothe correct depth, leaving the signal electrode layer intact.

After the leads have been connected to the crimp connectors and ametallic screen connected to the earth electrode has been arrangedacross the connection point if necessary, the connection point can bemade watertight by pressing silicone pads of a sufficient size onto itusing heat as an aid.

FIG. 6 further presents the cross-sectional structure of a sensormaterial according to the invention, which has a serpentine signalelectrode 52 placed between two sensor films, such as e.g. elasticplastic films 51 of a bubble structure, while the outermost layers arefilm-like earth electrodes 53 made of a conductive material and havingthe same size as the plastic films 51. The sensors can be produced bycutting a sensor material manufactured by a roll-to-roll techniquetransversely between two adjacent, parallel electrodes. In this case,too, as the signal electrode is sufficiently narrow, its cross-sectionalarea in relation to that of the entire sensor element is very small, andtherefore no disturbing interference will arise.

To the sensor element of the invention, it is possible to connect atransmitter-receiver apparatus for determining the intensity and pointof application of a force or pressure applied to the sensor from thesignals obtained from the sensor, comprising a transmitter unit workingin the microwave range which sends signals in the microwave range to thesignal electrode of the sensor, and a receiver unit which receives thesignals reflected back from the signal electrode.

To determine the intensity and point of application of a force orpressure applied to the sensor from voltage signals obtained from thesensor, it is possible to make use of the connecting strips 49 of asignal electrode as presented in FIG. 7. Based on the delay introducedby the resistance of the connecting strips, it is possible to determinethe point of application. By shaping the connecting strips in a zigzagfashion, thus increasing their length as much as possible, and using aline width as small as possible, their resistance can be increased, thusfacilitating the signal processing needed for the determination ofposition data.

It is obvious to the person skilled in the art that differentembodiments of the invention are not restricted to the example describedabove, but that they can be varied within the scope of the claimspresented below.

1. Method for manufacturing an electromechanical sensor element, inwhich method both surfaces of a sensor film are fitted with metallicelectrode films and the outer surface of at least one of the metallicelectrode films is fitted with a dielectric film, said sensor elementbeing produced by cutting the sensor element from a larger amount ofsensor element material, characterized in that, in the manufacture ofthe sensor element material, at least one of the electrodes is createdby printing a dielectric pattern corresponding to the electrode onto asurface of a metal film on the surface of the dielectric film in acontinuous processes from roll to roll and removing the metal from theareas outside the pattern by etching in a continuous process from rollto roll, and wherein the patterned film and the sensor film arelaminated together in a continuous process from roll to roll, andwherein at least one of the metallic electrode films comprises repeatedelectrode patterning.
 2. Method as defined in claim 1, wherein theelectrode patterning provided in the metallic electrode films are atleast partially interconnected via narrower connecting strips.
 3. Methodas defined in claim 1, wherein at least some of the connecting stripsare laid in a zigzag pattern.
 4. Method as defined in claim 1,characterized in that the electrodes are of band pattern and wherein aband-like sensor element is produced by cutting it from sensor elementmaterial comprising one or more continuous signal electrodes of equalwidth placed side by side.
 5. Method as defined in claim 1, wherein atleast some of the electrode patterning are of a polygonal shape. 6.Method as defined in claim 1, wherein at least some of the electrodepatterning comprise round shapes.
 7. Method as defined in claim 1,wherein the metallic electrode films comprise aluminum.
 8. Method asdefined in claim 1, characterized in that part of the surface of themetallic electrode films comprise printing with silver paste.
 9. Amethod for manufacturing an electromechanical sensor element, the sensorelement having an electrode, the method comprising steps of: (a) fittinga dielectric film to an outer surface of a metallic electrode film; (b)fitting the metallic electrode film to each surface of a sensor film toproduce a sensor element material; and (c) cutting the sensor elementfrom the sensor element material, wherein the electrode is created byprinting a dielectric pattern corresponding to the electrode onto asurface of a metal on a surface of the dielectric film in a continuousprocess from roll to roll and removing the metal from the areas outsidethe pattern by etching in a continuous process from roll to roll,wherein the dielectric film and patterned metallic electrode filmcomprise a combination, the combination and the sensor film arelaminated together in a continuous process from roll to roll, andwherein at least the metallic electrode film comprises repeatedelectrode patterning.